Practical management of hyperinsulinism in infancy

Pharmacological stimulation and inhibition of insulin secretion in mouse islets lacking ATP-sensitive K+ channels

BACKGROUND AND PURPOSE

ATP-sensitive potassium channels (K(ATP) channels) in beta cells are a major target for insulinotropic drugs. Here, we studied the effects of selected stimulatory and inhibitory pharmacological agents in islets lacking K(ATP) channels.

EXPERIMENTAL APPROACH

We compared insulin secretion (IS) and cytosolic calcium ([Ca(2+)](c)) changes in islets isolated from control mice and mice lacking sulphonylurea receptor1 (SUR1), and thus K(ATP) channels in their beta cells (Sur1KO).

KEY RESULTS

While similarly increasing [Ca(2+)](c) and IS in controls, agents binding to site A (tolbutamide) or site B (meglitinide) of SUR1 were ineffective in Sur1KO islets. Of two non-selective blockers of potassium channels, quinine was inactive, whereas tetraethylammonium was more active in Sur1KO compared with control islets. Phentolamine, efaroxan and alinidine, three imidazolines binding to K(IR)6.2 (pore of K(ATP) channels), stimulated control islets, but only phentolamine retained weaker stimulatory effects on [Ca(2+)](c) and IS in Sur1KO islets. Neither K(ATP) channel opener (diazoxide, pinacidil) inhibited Sur1KO islets. Calcium channel blockers (nimodipine, verapamil) or diphenylhydantoin decreased [Ca(2+)](c) and IS in both types of islets, verapamil and diphenylhydantoin being more efficient in Sur1KO islets. Activation of alpha(2)-adrenoceptors or dopamine receptors strongly inhibited IS while partially (clonidine > dopamine) lowering [Ca(2+)](c) (control > Sur1KO islets).

CONCLUSIONS AND IMPLICATIONS

Those drugs retaining effects on IS in islets lacking K(ATP) channels, also affected [Ca(2+)](c), indicating actions on other ionic channels. The greater effects of some inhibitors in Sur1KO than in control islets might be relevant to medical treatment of congenital hyperinsulinism caused by inactivating mutations of K(ATP) channels.

Investigation and management of congenital hyperinsulinism

Insulin is a powerful hormone produced by the beta-cells in the pancreas. Its major function is to regulate blood glucose levels, facilitating the transport of glucose into the body's cells. Congenital hyperinsulinism is characterized by the presence of insulin that is inappropriately high for the concentration of blood glucose. Because high levels of insulin also switch off all alternative fuels for the brain to use, this condition can cause brain injury if not detected quickly. Nurses are in a unique position by the bedside to identify the symptoms and treat the hypoglycaemia through very simple nursing interventions, such as safe administration of glucose and frequent blood glucose monitoring. Congenital hyperinsulinism can be transient or persistent. Persistent congenital hyperinsulinism can be further divided into focal or diffuse disease. Focal congenital hyperinsulinism can now be cured, and the management of congenital hyperinsulinism has radically changed with the help of genetics and research. Now pancreatectomy surgery is only used as the last resort.

Novel use of somatostatin receptor scintigraphy in localization of focal congenital hyperinsulinism: promising but fallible

Congenital hyperinsulinism (CHI) is the most common cause of persistent hypoglycemia in infants and children. The pre-operative differentiation of focal from diffuse forms is extremely important from the management point of view. The current methods for pre-operative differentiation are invasive. We report a patient with CHI where somatostatin receptor scintigraphy was used to diagnose CHI but with limited success. A preoperative 68gallium DOTATOC-PET scan was performed which revealed highly localized radiotracer uptake in the body of the pancreas. 80% of the pancreas including the body was resected. The clinical problems did not completely resolve after surgery. Histopathology revealed hyperplastic islet cells at the resected margin and randomly throughout the pancreas. This case highlights the use of 68gallium DOTATOC-PET scan in a patient with severe CHI. The satellite foci that were missed may be either an inherent limitation of 68Ga DOTATOC scan or an underinterpretation due to lack of expertise. This report opens up a new option of using somatostatin analogue scintigraphy for pre-operative localization of hyperplastic islet cells in patients with CHI.

Fluorine-18 DOPA-PET and PET/CT Imaging in Congenital Hyperinsulinism

Congenital hyperinsulinism is the principle cause of hypoglycemia during infancy but successful treatment is difficult and persistent hypoglycemia carries the risk of neurologic damage. Focal and diffuse abnormalities are the common forms of hyperinsulinism. Identification and localization of focal hyperinsulinism can be cured by partial pancreatectomy. It has been shown that affected pancreatic areas utilize LDOPA in a higher rate than normal pancreatic tissue and, thus, labeling L-DOPA with fluorine-18 (FDOPA) allows functional mapping of hyperinsulinism using PET. This article presents a fundamental overview of the genetics background, pathology, management, and the role of FDOPA-PET imaging in hyperinsulinism.

Update of mutations in the genes encoding the pancreatic beta-cell K(ATP) channel subunits Kir6.2 (KCNJ11) and sulfonylurea receptor 1 (ABCC8) in diabetes mellitus and hyperinsulinism

The beta-cell ATP-sensitive potassium (K(ATP)) channel is a key component of stimulus-secretion coupling in the pancreatic beta-cell. The channel couples metabolism to membrane electrical events bringing about insulin secretion. Given the critical role of this channel in glucose homeostasis it is therefore not surprising that mutations in the genes encoding for the two essential subunits of the channel can result in both hypo- and hyperglycemia. The channel consists of four subunits of the inwardly rectifying potassium channel Kir6.2 and four subunits of the sulfonylurea receptor 1 (SUR1). It has been known for some time that loss of function mutations in KCNJ11, which encodes for Kir6.2, and ABCC8, which encodes for SUR1, can cause oversecretion of insulin and result in hyperinsulinism of infancy, while activating mutations in KCNJ11 and ABCC8 have recently been described that result in the opposite phenotype of diabetes. This review focuses on reported mutations in both genes, the spectrum of phenotypes, and the implications for treatment on diagnosing patients with mutations in these genes.

Advances in the diagnosis and management of hyperinsulinemic hypoglycemia

Hyperinsulinemic hypoglycemia (HH) is a consequence of unregulated insulin secretion by pancreatic beta-cells and is a major cause of hypoglycemic brain injury and mental retardation. Congenital HH is caused by mutations in genes involved in regulation of insulin secretion, seven of which have been identified (ABCC8, KCNJ11, GLUD1, CGK, HADH, SLC16A1 and HNF4A). Severe forms of congenital HH are caused by mutations in ABCC8 and KCNJ11, which encode the two components of the pancreatic beta-cell ATP-sensitive potassium channel. Mutations in HNF4A, GLUD1, CGK, and HADH lead to transient or persistent HH, whereas mutations in SLC16A1 cause exercise-induced HH. Rapid genetic analysis combined with an understanding of the histological features (focal or diffuse disease) of congenital HH and the introduction of (18)F-L-3,4-dihydroxyphenylalanine PET-CT to guide laparoscopic surgery have totally transformed the clinical approach to this complex disease. Adult-onset HH is mostly caused by an insulinoma; however, it has also been reported to present as postprandial HH in patients with noninsulinoma pancreatogenous hypoglycemia syndrome, in those who have undergone gastric-bypass surgery for morbid obesity, and in those with mutations in the insulin-receptor gene.

[Hyperinsulinemic hypoglycemia in adults. Case reports and a short review]

Persistent hyperinsulinemic hypoglycemia (nesidioblastosis) not caused by an insulinoma is rare in adults. Morphologically no insulin secreting tumor is present. Keystones of diagnosis are not only low glucose levels but to maintain normoglycemia by use of intravenous glucose and the presence of high insulin and C-peptide levels. Noninvasive and invasive diagnostic techniques are required to rule out a hormone secreting tumor. Both conservative and/or surgical therapy are suggested to prevent damaging effects of repeated hypoglycemia.

CASE REPORT

Two patients with frequent and serious episodes of hypoglycemia are reported. In the 34-year-old female symptoms appeared with sweating, dizziness, trembling, nervousness and serious neuroglycopenic signs. In the 22-year-old male the main complaint was tympany, a rare and unusual sign of hypoglycemia, and intense feeling of esurience. The 24-hour fasting test was positive in both cases, i.e. it had to be stopped because of symptomatic hypoglycemia. No insulinoma could be localized, despite extensive search, therefore in both cases the diagnosis of adult-onset nesidioblastosis was set up, despite lack of histological confirmation. Diazoxide therapy resulted in symptom-free life for both patients.

CONCLUSION

Several diagnostic methods and treatment options are suggested for the rare disease nesidioblastosis to balance defective insulin secretion. However, once the decision is made in favour of surgical therapy, there is a thin line between successful treatment, persistence of the disease, and pancreatic insufficiency. Therefore it is worth considering to try conservative therapy especially when surgery is of high risk. Our cases suggest that diazoxide therapy is an effective and safe alternative in the treatment of adult-onset nesidioblastosis.

Identification of the Alzheimer's disease amyloid precursor protein (APP) and its homologue APLP2 as essential modulators of glucose and insulin homeostasis and growth

The amyloid precursor protein (APP), the source of the neurotoxic amyloid beta (A beta) peptide involved in Alzheimer's disease (AD), belongs to a conserved family of related proteins. In mammals, the APP family contains amyloid precursor-like protein 1 (APLP1) and amyloid precursor-like protein 2 (APLP2). Whilst a number of activities have been attributed to the APP family, an overall function has not been definitively established. While ablating either the APP or APLP2 gene in mice produces minimal phenotypic change, the combined knockout of these genes in mice causes postnatal mortality. Postnatal survival therefore requires a shared but unknown function of APP and APLP2. To investigate the biochemical basis for the postnatal lethality, plasma was analysed from double knockout mice (APP-/- APLP2-/-) 2 days before birth, at gestational day E17, and from mice at 12-16 h after birth. The postnatal double knockouts had 66% lower plasma glucose levels than their wild-type controls and 50% lower than their single knockout counterparts. Interestingly, the postnatal double knockouts displayed hyperinsulinaemia, as shown by inappropriate plasma insulin levels, given their degree of hypoglycaemia. The single knockout mice also showed hyperinsulinaemia and had 31% lower plasma glucose than the wild-types. While the double knockouts did not survive more than 24 h after birth, the single knockouts reached adulthood and their hypoglycaemia continued. Therefore, APP and APLP2 expression modulates plasma insulin and glucose concentrations. Plasma calcium, magnesium and phosphate were also significantly reduced in the double knockouts compared to the wild-types, and they showed distinctive growth restriction, suggesting the involvement of a metabolic impairment. These results link the expression of the APP and APLP2 genes with glucose homeostasis and growth and therefore identify a novel function for the APP family.

Alanine in HI: a silent mutation cries out!

It is a widely held paradigm in molecular biology that a change in the third base of a codon is silent in terms of expression. In this investigation, results are presented that challenge that paradigm, at least in terms of one polymorphism in KCNJ11, which is one of five genes that have been implicated in the disorder Hyperinsulinism of Infancy. In two cohorts of Australian patients, an uneven distribution of KCNJ11 SNP's was observed. A silent polymorphism at codon 190 was over-represented in the patients who responded well to medical treatment and under-represented in those that required radical surgical intervention. In an attempt to investigate this polymorphism, it was expressed in vitro and western blot analysis showed that there were virtually no bands from the homozygous variant samples, while strong bands were seen in normal controls. The human genome is highly redundant in terms of tRNA species for each amino acids but enigmatically under-represents a number of specific codons. The polymorphism in question occurs within one such codon. We propose that the presence of a base change at the third position of codon that is not represented by a corresponding anti-codon within the human nuclear tRNA leads to a decreased rate of expression of the protein.

The laparoscopic approach toward hyperinsulinism in children

Hyperinsulinemic hypoglycemia (HH) in children requiring surgery is rare. Early HH can be the result of focal or diffuse pancreatic pathology. A number of genetic abnormalities in early HH have been identified, but in the majority of patients no abnormality is found. The sporadic focal and diffuse forms as well the autosomal recessive form are particularly therapy-resistant and demand for early surgery. Preoperative discrimination between focal and diffuse disease in early HH is difficult. 18 F DOPA PET in combination with CT is promising as is laparoscopic exploration of the pancreas. Frozen section biopsy analysis has not been uniformly beneficial. If macroscopically no focal lesion is found, limited laparoscopic distal pancreatectomy provides tissue for definitive pathologic examination. Subsequent near total laparoscopic spleen-saving pancreatectomy surgery is not particularly difficult. Later HH may occur in the context of the MEN-1 syndrome and is then multifocal in nature. In MEN-1 patients, a distal spleen-saving pancreatectomy with enucleation of lesions in the head seems justified. Insulin-producing lesions in non-MEN-1 patients should be enucleated. There should always be a suspicion of malignancy. Also, in older children, surgery for hyperinsulinism should be performed laparoscopically.

Rapid intraoperative insulin assay: a novel method to differentiate insulinoma from nesidioblastosis in the pediatric patient

Introduction

Hyperinsulinism is the most common cause of recurrent and persistent hypoglycemia in infancy and childhood. Causes can include nesidioblastosis, pancreatic islet cell tumors such as insulinoma, and associations with multiple endocrine neoplasia syndromes. Although new, improved imaging techniques have allowed for more precise preoperative localization of insulinomas, the differentiation of nesidioblastosis and insulinoma, particularly in children, can be challenging. To improve intraoperative localization and confirmation of successful resection of insulinoma, a novel hormonal assay, the rapid intraoperative insulin assay, is reported for the first time in a pediatric patient. This intraoperative radioimmunoassay for insulin yields results within several minutes and confirms complete resection of insulinoma.

Case description

We present a case of pancreatic insulinoma in a child with symptoms of severe hypoglycemia, causing seizures. The insulinoma was enucleated laparoscopically, and rapid intra-operative insulin assay used to determine the success of the procedure.

Discussion and evaluation

This rapid intra-operative test provides a valuable adjunct for determining complete excision in complicated cases of recurrent or questionable insulinoma. Although not a common problem, for pediatric patients in whom the diagnosis is not clear, this test may provide a novel approach to confirming disease.

Conclusion

We propose the use of this assay in facilitating intra-operative resection and confirmation of complete excision in pediatric patients. This population may especially benefit from this novel assay to confirm complete resection and to differentiate multiple etiologies of hyperinsulinism.

Management of neonatal endocrinopathies--best practice guidelines

Neonatal emergencies are uncommon, but may lead to significant morbidity and mortality if not recognised and managed promptly. Disorders of sex development, hypoglycaemia, thyrotoxicosis and calcium balance are discussed, with emphasis on the clinical assessment, investigations and management of these disorders in the acute setting.

The role of ATP sensitive channels in insulin secretion and the implications in persistent hyperinsulinemic hypoglycaemia of infancy (PHHI)

Persistent Hyperinsulinemic Hypoglycaemia of Infancy (PHHI) is a metabolic syndrome of unregulated insulin secretion. It is a heterogenous disease with causes linked to mutations of the ATP sensitive potassium channels of the beta cell, as well as to metabolism in the beta cell. 5 candidate genes--ABCC8, KCNJ11, GCK, GLUD1 and SCHAD have been implicated in the disease so far, however the aetiology of the disease remains unknown in up to 50% of all patients. We genotyped 43 subjects with PHHI (20 surgically treated and 23 medically treated) for disease associated mutations in the candidate genes. Mutations on ABCC8 were identified in 16 of the 20 (80%) of the surgically treated patients. One putative mutation was identified in the medically treated cohort. The polymorphism E23K on KCNJ11 that is associated with NIDDM was differentially distributed in the 2 cohorts. We discuss the mutations identified, emphasise the importance of the K-ATP channel in physiological processes and discuss the possibility that the disease is caused by mutations in other genes associated with insulin release, glucose metabolism in the beta cell or beta cell apoptosis and survival. We propose that these processes must be explored in order to further our understanding of PHHI.

Development of pulmonary hypertension in an infant treated with diazoxide

Diazoxide is commonly used in the treatment of neonatal hyperinsulinism. We describe a one month-old infant who was treated with diazoxide for prolonged neonatal hyperinsulinism. Shortly after starting diazoxide, she was admitted to the hospital for tachypnea with hypoxemia, and was subsequently diagnosed with laryngomalacia and obstructive apnea. During hospitalization, her clinical course worsened due to the development of severe pulmonary hypertension, presumed due to diazoxide toxicity. Lung biopsy revealed a probable toxic vascular drug reaction. After discontinuing diazoxide, her clinical status improved and eventually returned to baseline.

Hyperinsulinaemic hypoglycaemia: biochemical basis and the importance of maintaining normoglycaemia during management

In patients with suspected hyperinsulinaemic hypoglycaemia, blood glucose concentrations should be maintained within the normal range during routine management

Severe hypoinsulinaemic hypoglycaemia in a premature infant associated with poor weight gain and reduced adipose tissue

BACKGROUND

Hypoglycaemia is common in preterm and intrauterine growth retarded (IUGR) newborns. Although preterm and IUGR infants have limited adipose tissue stores, the role of adipose tissue and the associated adipocytokines in glucose physiology is not known.

AIM

We report the case of a premature intrauterine growth retarded infant who had poor weight gain for the first 6 weeks of life and then developed severe hypoinsulinaemic hypoketotic hypoglycaemia.

RESULTS

There was markedly reduced adiposity with low serum leptin and adiponectin levels. Total energy expenditure and body composition measurements showed that body fat as a percentage of weight averaged 7% at 20 weeks and 28% at 28 weeks. At 20 weeks of age, the patient was equivalent to a deficit of >2 SD scores of body fat, but average fatness by 28 weeks. The hypoglycaemia completely resolved when the patient started gaining weight with an increase in fat mass and a concomitant increase in serum leptin and adiponectin level.

CONCLUSIONS

Although the precise mechanism of this patient's severe hypoglycaemia is unclear, further studies are required to understand the role of adipose tissue and adipocytokines in glucose homeostasis in preterm and IUGR infants.

Molecular mechanisms of neonatal hyperinsulinism

Congenital hyperinsulinism (CHI), characterized by profound hypoglycaemia related to inappropriate insulin secretion, may be associated histologically with either diffuse insulin hypersecretion or focal adenomatous hyperplasia, which share a similar clinical presentation, but result from different molecular mechanisms. Whereas diffuse CHI is of autosomal recessive, or less frequently of autosomal dominant, inheritance, focal CHI is sporadic. The most common mechanism underlying CHI is dysfunction of the pancreatic ATP-sensitive potassium channel (K(+)(ATP)). The two subunits of the K(+)(ATP) channel are encoded by the sulfonylurea receptor gene (SUR1 or ABCC8) and the inward-rectifying potassium channel gene (KIR6.2 or KCNJ11), both located in the 11p15.1 region. Germ-line, paternally inherited, mutations of the SUR1 or KIR6.2 genes, together with somatic maternal haplo-insufficiency for 11p15.5, were shown to result in focal CHI. Diffuse CHI results from germ-line mutations in the SUR1 or KIR6.2 genes, but also from mutations in several other genes, namely glutamate dehydrogenase (with associated hyperammonaemia), glucokinase, short-chain L-3-hydroxyacyl-CoA dehydrogenase, and insulin receptor gene. Hyperinsulinaemic hypoglycaemia may be observed in several overlapping syndromes, such as Beckwith-Wiedemann syndrome (BWS), Perlman syndrome, and, more rarely, Sotos syndrome. Mosaic genome-wide paternal isodisomy has recently been reported in patients with clinical signs of BWS and CHI. The primary causes of CHI are genetically heterogeneous and have not yet been completely unveiled. However, secondary causes of hyperinsulinism have to be considered such as fatty acid oxidation deficiency, congenital disorders of glycosylation and factitious hypoglycaemia secondary to Munchausen by proxy syndrome.

Mutations in the genes encoding the pancreatic beta-cell KATP channel subunits Kir6.2 (KCNJ11) and SUR1 (ABCC8) in diabetes mellitus and hyperinsulinism

The beta-cell ATP-sensitive potassium channel is a key component of stimulus-secretion coupling in the pancreatic beta-cell. The channel couples metabolism to membrane electrical events, bringing about insulin secretion. Given the critical role of this channel in glucose homeostasis, it is not surprising that mutations in the genes encoding for the two essential subunits of the channel can result in both hypo- and hyperglycemia. The channel consists of four subunits of the inwardly rectifying potassium channel Kir6.2 and four subunits of the sulfonylurea receptor 1. It has been known for some time that loss of function mutations in KCNJ11, which encodes for Kir6.2, and ABCC8, which encodes for SUR1, can cause oversecretion of insulin and result in hyperinsulinemia (HI) of infancy; however, heterozygous activating mutations in KCNJ11 that result in the opposite phenotype of diabetes have recently been described. This review focuses on reported mutations in both genes, the spectrum of phenotypes, and the implications for treatment when patients are diagnosed with mutations in these genes.

The diagnosis of ectopic focal hyperinsulinism of infancy with [18F]-dopa positron emission tomography

BACKGROUND

Congenital hyperinsulinism (CHI) is a cause of severe hypoglycemia in the neonatal and infancy period. Histologically, there are two subtypes with diffuse and focal disease. The preoperative differentiation of these two forms is very important because the surgical management is radically different. The focal form of the disease can be cured if the focal lesion can be localized accurately and completely resected with surgery.

AIM

We report the case of a child who underwent three pancreatectomies with a choledochoduodenostomy and a cholecystectomy but continued to have severe hyperinsulinemic hypoglycemia.

METHODS/RESULTS

Radiological investigations including imaging with (18)fluoro-L-Dopa positron emission tomography scan showed a clear focus of increased (18)F-fluoro-L-Dopa uptake in the vicinity of the former head of the pancreas. On the magnetic resonance imaging scan, this focal uptake appeared to localize adjacent or next to duodenum (in the wall or cavity of the duodenum).

CONCLUSIONS

This unique case highlights the importance of correctly localizing and completely resecting the focal lesion in patients with CHI. (18)Fluoro-L-Dopa positron emission tomography scan can identify ectopic focal lesions in patients with CHI.

Hiperinsulinismo congénito. Revisión de 22 casos

INTRODUCTION

Congenital hyperinsulinism (CHI) is the most common cause of recurrent episodes of hypoglycemia in early childhood and consists of a group of distinct genetic disorders causing dysregulation of insulin secretion.

OBJECTIVE

To review the presentation, management and outcome of patients with CHI attended at our hospital.

MATERIAL AND METHODS

A retrospective review of all patients diagnosed with CHI between 1982 and 2004 was performed. Data were collected on age, gender, clinical presentation, medical and surgical management, and complications.

RESULTS

Twenty-two patients were identified. Notable features were early symptom onset in 80 %, pancreatectomy in 72 %, and neurological sequels in 28 % (abnormal neurodevelopment in 22 % and epilepsy in 13 %).

CONCLUSIONS

The presentation, management and outcome in our patients were similar to those in other series, indicating the need for early diagnosis and treatment to avoid neurological sequels.

Malignant insulinoma in childhood

Pancreatic tumors constitute a rare surgical problem in infancy and childhood. Insulinomas are rare in all age groups with an estimated incidence of one per 250,000 person-years and even rarer in childhood. We report a 10 year-old girl with malignant insulinoma. The presenting symptom was hypoglycemic attacks. Laboratory investigation demonstrated that the hypoglycemia was due to hyperinsulinism. MRI of the abdomen revealed a mass at the tail of the pancreas. Distal pancreatectomy with splenectomy was performed. Histological examination showed malignant insulinoma with peripancreatic lymph node metastases. One month later abdominal MRI revealed the existence of multiple small metastatic foci in the liver, which were confirmed by In111 octreoscan. Treatment with octreotide was started and the disease is stable after 12 months of therapy.

[Octreotide therapy for persistent hyperinsulinemic hypoglycemia of infancy]

This paper presents a clinical case of persistent hyperinsulinemic hypoglycemia of infancy (PHHI) and a literature review on this subject. We report on a newborn who presented with hypoglycemic episodes in her first 24 hs of life and was treated successfully with octreotide until the moment. PHHI is the most common cause of persistent hyperinsulinism in infancy and can be hazardous for the development of the central nervous system. There are few current options for clinical treatment, with variable efficacy, and octreotide seems to be the best option before surgical treatment, the only way to control the disease. Preoperative evaluation allows one to adequately distinguish between focal or diffuse processes and suggests the extension of pancreatic resection, improving surgical results and reducing the incidence of postoperative sequelae. Partial pancreatectomy is the procedure of choice in focal disease.

[Congenital hyperinsulinism in newborn and infant]

Congenital hyperinsulinism (HI) is the most important cause of hypoglycaemia in early infancy. The inappropriate oversecretion of insulin is responsible for profound hypoglycaemias requiring aggressive treatment to prevent severe and irreversible brain damage. Several classifications of HI can be attempted, based on: 1) the onset of hypoglycemia in the neonatal period or later in infancy; 2) the histological lesion: focal or diffuse; 3) the genetic transmission: sporadic, recessive, or less frequently dominant. The most common underlying mechanism of HI is dysfunction of the pancreatic ATP-sensitive potassium channel (K(+)(ATP)). The 2 subunits of the K(+)(ATP) channel are encoded by either the sulfonylurea receptor gene (SUR1 or ABCC8) or the inward-rectifying potassium channel gene (KIR6.2. or KCNJ11), both located in the 11p15.1 region. Focal CHI has been shown to result from a paternally inherited mutation on the SUR1 or KIR6.2 gene and loss of the maternal 11p15 allele restricted to the pancreatic lesion. Diffuse HI, frequently due to mutations of the SUR1 or KIR6.2 genes of autosomal recessive inheritance is genetically heterogeneous. The distinction between the focal and the diffuse HI is very important, because the treatments are different. To distinguish between focal and diffuse HI, transhepatic catheterisation with pancreatic venous sampling was the reference technique, but will likely be replaced by [(18)F] Fluoro-L-Dopa PET scan, which is easier to perform. In absence of response to the medical treatment (diazoxide) a limited pancreatectomy permits to cure focal HI, while a diffuse HI requires a subtotal pancreatectomy with high risk of subsequent diabetes mellitus.

Serum glucagon counterregulatory hormonal response to hypoglycemia is blunted in congenital hyperinsulinism

The mechanisms involved in the release of glucagon in response to hypoglycemia are unclear. Proposed mechanisms include the activation of the autonomic nervous system via glucose-sensing neurons in the central nervous system, via the regulation of glucagon secretion by intra-islet insulin and zinc concentrations, or via direct ionic control, all mechanisms that involve high-affinity sulfonylurea receptor/inwardly rectifying potassium channel-type ATP-sensitive K(+) channels. Patients with congenital hyperinsulinism provide a unique physiological model to understand glucagon regulation. In this study, we compare serum glucagon responses to hyperinsulinemic hypoglycemia versus nonhyperinsulinemic hypoglycemia. In the patient group (n = 20), the mean serum glucagon value during hyperinsulinemic hypoglycemia was 17.6 +/- 5.7 ng/l compared with 59.4 +/- 7.8 ng/l in the control group (n = 15) with nonhyperinsulinemic hypoglycemia (P < 0.01). There was no difference between the serum glucagon responses in children with diffuse, focal, and diazoxide-responsive forms of hyperinsulinism. The mean serum epinephrine and norepinephrine concentrations in the hyperinsulinemic group were 2,779 +/- 431 pmol/l and 2.9 +/- 0.7 nmol/l and appropriately rose despite the blunted glucagon response. In conclusion, the loss of ATP-sensitive K(+) channels and or elevated intraislet insulin cannot explain the blunted glucagon release in all patients with congenital hyperinsulinism. Other possible mechanisms such as the suppressive effect of prolonged hyperinsulinemia on alpha-cell secretion should be considered.

Congenital hyperinsulinism

Congenital hyperinsulinism is a cause of persistent hypoglycaemia in the neonatal period. It is a heterogeneous disease with respect to clinical presentation, molecular biology, genetic aetiology and response to medical therapy. The clinical heterogeneity may range from severe life-threatening disease to very mild clinical symptoms. Recent advances have begun to clarify the molecular pathophysiology of this disease, but despite these advances treatment options remain difficult and there are many long-term complications. So far mutations in five different genes have been identified in patients with congenital hyperinsulinism. Most cases are caused by mutations in genes coding for either of the two subunits of the beta-cell K(ATP) channel (ABCC8 and KCNJ11). Two histological subtypes of the disease - diffuse and focal - have been described. The preoperative histological differentiation of these two subtypes is now mandatory as surgical management will be radically different. The ability to distinguish diffuse from focal lesions has profound implications for therapeutic approaches, prognosis and genetic counselling.

The investigation and management of neonatal hypoglycaemia

Assessment of neonatal glycaemic status requires accurate and reliable measurement of blood glucose concentrations. Most point-of-care technologies are, however, unsuitable for use in neonates. Although the definition of hypoglycaemia remains elusive, current knowledge allows adoption of pragmatic threshold blood glucose concentrations when clinical intervention should be considered. The vast majority of instances of neonatal hypoglycaemia are due to problems with the normal processes of metabolic adaptation after birth, and strategies to enhance the normal adaptive processes should help prevent such episodes. Further investigations and specific interventions should be considered when hypoglycaemia is of unusual severity or occurs in an otherwise low-risk infant.

Congenital hyperinsulinism and mosaic abnormalities of the ploidy

BACKGROUND

Congenital hyperinsulinism and Beckwith-Wiedemann syndrome both lead to beta islet hyperplasia and neonatal hypoglycaemia. They may be related to complex genetic/epigenetic abnormalities of the imprinted 11p15 region. The possibility of common pathophysiological determinants has not been thoroughly investigated.

OBJECTIVE

To report abnormalities of the ploidy in two unrelated patients with congenital hyperinsulinism.

METHODS

Two patients with severe congenital hyperinsulinism, one overlapping with Beckwith-Wiedemann syndrome, had pancreatic histology, ex vivo potassium channel electrophysiological studies, and mutation detection of the encoding genes. The parental genetic contribution was explored using genome-wide polymorphism, fluorescent in situ hybridisation (FISH), and blood group typing studies.

RESULTS

Histological findings diverged from those described in focal congenital hyperinsulinism or Beckwith-Wiedemann syndrome. No potassium channel dysfunction and no mutation of its encoding genes (SUR1, KIR6.2) were detected. In patient 1 with congenital hyperinsulinism and Beckwith-Wiedemann syndrome, paternal isodisomy for the whole haploid set was homogeneous in the pancreatic lesion, and mosaic in the leucocytes and skin fibroblasts (hemihypertrophic segment). Blood group typing confirmed the presence of two erythroid populations (bi-parental v paternal only contribution). Patient 2 had two pancreatic lesions, both revealing triploidy with paternal heterodisomy. Karyotype and FISH analyses done on the fibroblasts and leucocytes of both patients were unremarkable (diploidy).

CONCLUSIONS

Diploid (biparental/paternal-only) mosaicism and diploid/triploid mosaicism were present in two distinct patients with congenital hyperinsulinism. These chromosomal abnormalities led to paternal disomy for the whole haploid set in pancreatic lesions (with isodisomy or heterodisomy), thereby extending the range and complexity of the mechanisms underlying congenital hyperinsulinism, associated or not with Beckwith-Wiedemann syndrome.

Ketotic hypoglycaemia in children with diazoxide responsive hyperinsulinism of infancy

Hyperinsulinism of infancy (HI) is a cause of persistent and recurrent hypoglycaemia in infancy and childhood, which if untreated can cause significant brain damage and mental retardation. The biochemical hallmark of hyperinsulinism is hypofattyacidaemic, hypoketotic hyperinsulinaemic hypoglycaemia. Diazoxide is the first line medical treatment for persistent HI. Diazoxide is an agonist of the pancreatic beta-cell KATP channel and inhibits insulin secretion. Children who develop recurrent hypoglycaemia while on therapy with diazoxide are thought to be unresponsive to this medication or non compliant with medical therapy. We report a novel observation of "ketotic" hypoglycaemia in two children on diazoxide therapy for persistent HI. Detailed assessment of the intermediary metabolites and hormones at the time of the hypoglycaemia showed appropriate insulin suppression with appropriate increases in the serum levels of non-esterified fatty acids and ketone bodies as well as an intact counter-regulatory hormone response. The precise mechanism of the hypoglycaemia is unclear.

CONCLUSION

These cases illustrate that recurrent hypoglycaemia while on diazoxide therapy may be due to other mechanisms and does not imply diazoxide unresponsiveness or non-compliance.

From congenital hyperinsulinism to diabetes mellitus: the role of pancreatic beta-cell KATP channels

Pancreatic beta-cell adenosine triphosphate (ATP)-sensitive potassium (K(ATP)) channels play a pivotal role in linking glucose metabolism to regulated insulin secretion. K(ATP) channels are hetero-octameric complexes comprising two subunits Kir6.2 and sulfonylurea receptor 1 (SUR1). Changes in the intracellular concentration of nucleotides (ATP) cause alterations in the resting and opening state of the K(ATP) channels. Loss-of-function mutations in the genes encoding the two subunits of K(ATP) channels lead to the most common form of congenital hyperinsulinism (CHI). This causes persistent and severe hypoglycemia in the neonatal and infancy period. CHI can cause mental retardation and epilepsy if not treated properly. On the other hand, now there is evidence of an association between polymorphisms in the Kir6.2 gene and type 2 diabetes mellitus, mutations in the Kir6.2 gene and neonatal diabetes mellitus, and mutations in the SUR1 gene and diabetes mellitus. Interestingly, for reasons that are unclear at present, mice knockout models of K(ATP) channels are different from the human phenotype of CHI. This article is a review focusing on how abnormalities in the pancreatic beta-cell K(ATP) channels can lead to severe hypoglycemia on the one hand and diabetes mellitus on the other.

Hyperinsulinisme persistant du nouveau-né et du nourrisson : traitement chirurgical des lésions pancréatiques focales dans 60 cas

Congenital hyperinsulinism of infancy is a severe disease that leads to important brain damage. Two different forms of the disease have been identified by pathologists: a diffuse and a focal form. A specific genetic anomaly identified in focal forms has never been described in diffuse ones. However, for most of authors, failure of medical treatment results in near-total pancreatectomy in all cases, which ends in diabetus. The aim of this retrospective study was to assess the results of elective partial pancreatectomy performed in 60 cases of focal form of hyperinsulinism over the last 18 years. Fifty-eight patients were cured with euglycemia at both fasting and hyperglycaemic tests without insulin-dependent diabetes mellitus. One patient is still in hypoglycaemia from unrecognized lesion; insulin-dependent diabetes mellitus occurred in one case nine years after surgery (a near-total pancreatectomy has been performed because of unknown focal form, in 1985).

Contemporary strategies in the diagnosis and management of neonatal hyperinsulinaemic hypoglycaemia

Congenital hyperinsulinism (CHI) is a genetically and phenotypically diverse syndrome. Key management issues involve early diagnosis by ensuring that appropriate samples are taken at the point of hypoglycaemia, prevention of recurrent hypoglycaemia, and detailed characterisation of the clinical, biochemical, and genetic features of each case. Infants with persistent diazoxide resistant CHI require evaluation at specialist referral centres equipped to differentiate those with focal (fo-HI) and diffuse (di-HI) pancreatic disease. Fo-HI is treated with selective pancreatic resection but di-HI is treated by surgery only if intensive medical management regimes are not efficacious.

Mechanism, temporal patterns, and magnitudes of the metabolic responses to the KATP channel agonist diazoxide

To assess the mechanism, temporal patterns, and magnitudes of the metabolic responses to the ATP-dependent potassium channel agonist diazoxide, neuroendocrine and metabolic responses to intravenous diazoxide (saline, 1.0 and 2.0 mg/kg) and oral diazoxide (placebo, 4.0 and 6.0 mg/kg) were assessed in healthy young adults. Intravenous diazoxide produced rapid, but transient, decrements (P = 0.0023) in plasma insulin (e.g., nadirs of 2.8 +/- 0.5 and 1.8 +/- 0.3 microU/ml compared with 7.0 +/- 1.0 microU/ml after saline at 4.0-7.5 min) and C-peptide (P = 0.0228) associated with dose-related increments in plasma glucose (P = 0.0044) and serum nonesterified fatty acids (P < 0.0001). After oral diazoxide, plasma insulin appeared to decline, as did C-peptide, again associated with dose-related increments in plasma glucose (P < 0.0001) and serum nonesterified fatty acids (P = 0.0141). Plasma glucagon, as well as cortisol and growth hormone, was not altered. Plasma epinephrine increased (P = 0.0215) slightly only after intravenous diazoxide. There were dose-related increments in plasma norepinephrine (P = 0.0038 and P = 0.0005, respectively), undoubtedly reflecting a compensatory sympathetic neural response to vasodilation produced by diazoxide, but these would not raise plasma glucose or serum nonesterified fatty acid levels. Thus selective suppression of insulin secretion, without stimulation of glucagon secretion, raised plasma glucose and serum nonesterified fatty acid concentrations. These findings define the temporal patterns and magnitudes of the metabolic responses to diazoxide and underscore the primacy of regulated insulin secretion in the physiological regulation of postabsorptive carbohydrate and lipid metabolism.

Y-26763: ATP-sensitive K+ channel activation and the inhibition of insulin release from human pancreatic beta-cells

The effect of Y-26763 [(-)-(3S,4R)-4-(N-acetyl-N-hydroxyamino)-6-cyano-3,4-dihydro-2,2-dimethyl-2H-1-benzopyran-3-ol], a novel ATP-sensitive K(+) (K(ATP)) channel activator, was tested on insulin secretion from human pancreatic islets in vitro. Y-26763 was able to inhibit both glucose- and tolbutamide-induced insulin secretion from islets as assessed by radioimmunoassay. The mechanism for inhibition of insulin secretion was characterised using patch clamp electrophysiology on dispersed human pancreatic beta-cells which express K(ATP) channels comprised of Kir6.2 and SUR1, and the NES2Y human beta-cell line, transfected with Kir6.2DeltaC26. Y-26763 activated K(ATP) channels in a reversible manner with a similar activity to diazoxide. This required the presence of hydrolysable nucleotides and appeared to be mediated by interaction of Y-26763 with SUR1 since: (a) tolbutamide was able to reverse the actions of Y-26763 and (b) Y-26763 failed to activate Kir6.2DeltaC26 in the absence of SUR1. We conclude that Y-26763-induced inhibition of insulin release is dependent upon the activation of K(ATP) channels in human beta-cells.

Hyperinsulinism of infancy: novel ABCC8 and KCNJ11 mutations and evidence for additional locus heterogeneity

Hyperinsulinism of infancy is a genetically heterogeneous disease characterized by dysregulation of insulin secretion resulting in severe hypoglycemia. To date, mutations in five different genes, the sulfonylurea receptor (SUR1, ABCC8), the inward rectifying potassium channel (K(IR)6.2, KCNJ11), glucokinase (GCK), glutamate dehydrogenase (GLUD1), and short-chain 3-hydroxyacyl-coenzyme A dehydrogenase (SCHAD), have been implicated. Previous reports suggest that, in 40% of patients, no mutation can be identified in any of these genes, suggesting additional locus heterogeneity. However, previous studies did not screen all five genes using direct sequencing, the most sensitive technique available for mutation detection. We selected 15 hyperinsulinism of infancy patients and systematically sequenced the promoter and all coding exons and intron/exon boundaries of ABCC8 and KCNJ11. If no mutation was identified, the coding sequence and intron/exon boundaries of GCK, GLUD1, and SCHAD were sequenced. Seven novel mutations were found in the ABCC8 coding region, one mutation was found in the KCNJ11 coding region, and one novel mutation was found in each of the two promoter regions screened. Functional studies on beta-cells from six patients showed abnormal ATP-sensitive K+ channel function in five of the patients; the sixth had normal channel activity, and no mutations were found. Photolabeling studies using a reconstituted system showed that all missense mutations altered intracellular trafficking. Each of the promoter mutations decreased expression of a reporter gene by about 60% in a heterologous expression system. In four patients (27%), no mutations were identified. Thus, further genetic heterogeneity is suggested in this disorder. These patients represent a cohort that can be used for searching for mutations in other candidate genes.

Nesidioblastosis: An Old Term and a New Understanding

Nesidioblastosis is a clinically, pathologically, and genetically heterogeneous disease. Differences between well described forms in neonates with persistent hyperinsulinemic hypoglycemia of infancy (PHHI) and rare forms in adults are described. Histopathologic criteria include hypertrophic islets occasionally showing beta cells with pleomorphic nuclei, ductuloinsular complexes, and neoformation of islets from ducts. These changes can be found as diffuse or focal forms of nesidioblastosis. Although most cases occur sporadically, several genetic defects ( SUR1, Kir6.2, GCK, and GLUD1 genes) have been described in neonates. In adults a higher rate of nesidioblastosis is observed in conjunction with multiple endocrine neoplasia type 1. The disease is diagnosed biochemically by a supervised fasting test in adults and in neonates by determining the glucose requirements to maintain normoglycemia, inappropriately high insulin and c-peptide levels, low free fatty acid and ketone body concentrations, glycemic response to glucagons, and the absence of ketonuria. If all highly selective noninvasive imaging techniques fail to identify a tumor, selective arterial calcium stimulation testing for gradient-guided surgery in adults and percutaneous transhepatic pancreatic venous sampling in neonates should be performed. a 95% pancreatectomy is necessary in neonates with a diffuse form of nesidioblastosis, whereas focal forms can be treated by partial pancreatectomy.

Hyperinsulinaemic hypoglycaemia in infancy and childhood--resolving the enigma

Children with severe hypoglycaemia due to persistent hyperinsulinism in infancy (HI) generate some of the most formidable problems of management in contemporary paediatric endocrinology. Until recently its pathophysiology was an enigma, although it was thought to be due to an anatomical abnormality in the islets of Langerhans (so called 'nesidioblastosis'). During the last 6 years there has been an explosion of knowledge providing fundamental insights into the pathological mechanisms underpinning the abnormal insulin secretion. This knowledge has been facilitated by ENRHI, a programme of research funded by the European Union, which brings together clinicians and basic scientists from 14 different countries. This collaboration encompasses clinical paediatric endocrinology, intracellular biochemistry, membrane physiology and molecular biology. This collaboration has resulted in numerous publications generating new insights into the pathophysiology of HI and represents a paradigm for collaboration in paediatric endocrinology. This review article is based on a plenary lecture delivered at the European Society for Paediatric Endocrinology meeting in Montreal on behalf of the European Network for Research into Hyperinsulinism of Infancy (ENRHI).

Laparoscopic diagnosis and cure of hyperinsulinism in two cases of focal adenomatous hyperplasia in infancy

Persistent hyperinsulinemic hypoglycemia of infancy or congenital hyperinsulinism of the neonate is a rare condition that may cause severe neurologic damage if the disease is unrecognized or inadequately treated. Current treatment aims to restore normal blood glucose levels by providing a carbohydrate-enriched diet and drugs that inhibit insulin secretion. If medical treatment fails, then surgery is required. Because congenital hyperinsulinism may be caused either by diffuse involvement of pancreatic beta-cells or by a focal cluster of abnormal beta-cells, the extent of pancreatectomy varies. We report on 2 patients with a focal form of the disease for whom diagnosis was made with laparoscopy. Laparoscopic enucleation of the lesion was curative.

Blood Glucose Control During Selective Arterial Stimulation and Venous Sampling for Localization of Focal Hyperinsulinism Lesions in Anesthetized Children

Surgical management of congenital hyperinsulinism is improved by accurate localization of small, focal dysregulated pancreatic lesions using the arterial stimulation and venous sampling (ASVS) test, which can demonstrate increased hepatic venous insulin concentrations after selective arterial injections of calcium. However, anesthesia-related increases in blood glucose can induce insulin secretion, making it difficult to interpret ASVS test data. In this retrospective study, we examined the effect of anesthetic interventions on blood glucose concentrations in 68 children undergoing ASVS testing. We considered only the glucose concentrations observed before calcium stimulation in the final analysis. The choice of drugs for induction (sevoflurane, propofol, or thiopentone), maintenance inhaled anesthetics (sevoflurane, desflurane, or isoflurane), and the use of caudal epidural bupivacaine were not associated with significant differences in the mean blood glucose concentration before ASVS. However, patients receiving remifentanil infusions had smaller mean glucose concentrations (80 +/- 18 versus 100 +/- 44 mg x dl(-1), P = 0.01). These concentrations were also significantly smaller if tracheal intubation was delayed for at least 10 min after induction while patients received inhaled anesthetics via a face mask along with remifentanil infusions (79 +/- 14 for delayed intubation versus 95 +/- 39 mg x dl(-1) for early intubation, respectively, P = 0.03). The percentage increase in glucose concentrations from preintubation values was significantly smaller in these subjects (3.7% +/- 21.9% for delayed intubation versus 31.7% +/- 60.4% for early intubation, P = 0.02). We conclude that the anesthetic management protocol for these patients should include the use of remifentanil infusions and the administration of inhaled anesthetics and remifentanil infusions for a minimum of 10 min to establish a deep plane of anesthesia before tracheal intubation.

Hypoketotic hypofattyacidaemic hypoinsulinaemic hypoglycaemia in a child with hemihypertrophy? A new syndrome

BACKGROUND

Recurrent and persistent hypoketotic, hypofattyacidaemic hypoglycaemia in infancy and childhood is most frequently due to hyperinsulinism of infancy. This biochemical profile can also be due to non-islet cell tumour hypoglycaemia or circulating insulin-receptor autoantibodies. Hyperinsulinaemic hypoglycaemia is also seen in children with the Beckwith-Wiedemann syndrome, where it is usually transient.

METHODS/RESULTS

We report a novel case of child with hemihypertrophy and severe persistent hypoketotic, hypofattyacidaemic hypoinsulinaemic hypoglycaemia. No 'big' pro-IGF2 forms or circulating insulin-receptor antibodies were found. Glucose and protein isotope turnover studies showed marked suppression of hepatic glucose production during fasting. There was no evidence for constitutive autophosphorylation of the insulin or IGF-1 receptor, and no evidence for up-regulation of IGF-1 receptor.

CONCLUSION

The precise pathophysiology of this novel case is still unclear.

Síndrome de hiperinsulinismohiperamoniemia por mutación de novo en el exón 7 (G979A) del gen GLUD-1,con excelente respuesta a diazóxido

Hyperinsulinism-hyperammonemia syndrome is characterized by recurrent and symptomatic hypoglycemias in childhood, secondary to hyperinsulinism associated with mild and asymptomatic hyperammonemia. This syndrome is caused by dominantly expressed mutations of the glutamate dehydrogenase gene (10q23.3). These mutations modify control of enzyme activity and represent the second cause of congenital hyperinsulinism of known genetic etiology. Moreover, this syndrome is the first genetic disorder due to an increase of function in an enzyme of intermediary metabolism to have been identified. We present the case of a 16-month-old boy with symptomatic recurrent hypoglycemias from the end of the first year of life, caused by a de novo mutation in exon 7 (G979A) of the GDH gene, with excellent outcome after diazoxide treatment.

Severe transient hyperinsulinaemic hypoglycaemia: two neonates without predisposing factors and a review of the literature

We report on transient hyperinsulinism (HI), presenting as severe congenital HI, in two neonates born without intrauterine growth restriction, maternal diabetes, perinatal asphyxia or Rhesus/platelet isoimmunisation. The neonates developed early (<6 h of life), symptomatic, non-ketotic hypoglycaemia (0-0.66 mmol/l), associated with elevated insulin levels (40-200 mU/l), and required high glucose infusion rates (22-24 mg/kg per min) to maintain normoglycaemia. However, both babies were diazoxide-sensitive and did not require glucose infusions beyond 2 weeks of life. Neither neonate had elevated serum ammonia levels or evidence of a metabolic disorder.

CONCLUSION

Transient hyperinsulinism can occur in newborns delivered uneventfully without significant perinatal complications. The unusual sensitivity to medical treatment in these cases of neonatal-onset hyperinsulinaemic hypoglycaemia underscores the importance of careful medical management of severe congenital hyperinsulinism. Careful consideration of the indication and if necessary, timing and extent of pancreatectomy is required, while maintaining euglycaemia to protect the developing brain.

Focal and diffuse forms of congenital hyperinsulinism: the keys for differential diagnosis

Congenital hyperinsulinism is clinically characterized by an inappropriate insulin secretion resulting in recurrent severe hypoglycemia. Nesidioblastosis, the proliferation of islets cells budding off from pancreatic ducts, has been considered for years as the histological lesion responsible for the syndrome. In our morphological studies, we demonstrated that nesidioblastosis is not specific for the disease, which is actually not a single entity. Indeed, we recognized the existence of two different forms--a diffuse form and a focal form--and demonstrated that they can be differentiated on the basis of morphological criteria, even on frozen sections during surgery. This histological distinction directs the therapeutic approach because the patients suffering from the focal form of the syndrome can be completely cured by a very limited pancreatectomy. Molecular findings confirmed the reliability of this histological distinction, showing a specific genetic background for each form.

Hyperinsulinaemic hypoglycaemia in preterm neonates

Hyperinsulinism in infancy (HI) is an important cause of severe and recurrent hypoglycaemia in newborn infants. It usually appears in infants born at term, and only one case of its occurrence in a prematurely born infant has been reported as an incidental finding. This is a report of seven infants born at 31-36 weeks gestation who experienced severe persistent hyperinsulinism. Two infants were large for dates. All infants were difficult to manage, suggesting that the occurrence of HI with prematurity may be associated with a particularly aggressive illness. HI should be considered in the differential diagnosis of severe hypoglycaemia in preterm infants.

Hyperinsulinism in infancy: understanding the pathophysiology

Hyperinsulinism in infancy (HI) is the commonest cause of persistent and recurrent hypoglycaemia in the infancy and childhood period. HI is a heterogeneous disorder with respect to clinical presentation, histology, molecular biology and genetics. Recent advances have provided unique insights into the pathophysiology of this intriguing disease as well as providing an understanding of the normal physiological and biochemical mechanisms regulating insulin secretion from pancreatic beta-cells. The histological differentiation of focal and diffuse forms of HI has radically changed the surgical management to this disease. So far mutations in five different genes have been described which lead to dysregulated insulin secretion from beta-cells. Despite these advances the genetic defect is still unknown in about 60% of cases.

Surgery of persistent hyperinsulinaemic hypoglycaemia

Hyperinsulinism (HI) is the commonest cause of persistent or recurrent hypoglycaemia in childhood. HI is genetically and phenotypically diverse. Key management issues involve early diagnosis by insuring that appropriate investigations are undertaken at the point of hypoglycaemia, prevention of recurrent hypoglycaemia and clinical, biochemical and genetic characterisation of the HI syndrome. Children with persistent diazoxide resistant HI require investigation at specialist centres to differentiate those with a generalised disorder of the pancreas (diffuse HI; di-HI) from those with localised abnormalities within the pancreas (focal HI; fo-HI). Fo-HI may be managed by selective pancreatic resection of the focal abnormality. Di-HI is only managed by surgery if combination drug therapies are unable to prevent hypoglycaemia. Pancreatic beta-cell dysfunction persists following subtotal pancreatectomy of di-HI.